Making a custom stitch z brush
It seems a bit tedious to paint a b&amp;w stitch directly in Blender but you can:

Create a stitch on a flat plane:



Choose the top view, in Solid mode, in the Viewport Shading panel, choose Matcap and choose the normal matcap:



In the View menu, choose Viewport Render Image:



In an image editor, only keep the normal map image:



Unwrap your object and use the image in an Image Texture plugged into a Normal map in order to create your stitch: